fix(ci): drop the cache steps this runner cannot serve

actions/cache expects a cache service the runner matching Gitea 1.20 does not
speak, and it failed the job outright. It was an optimisation; the source
fallback that makes the install work is what mattered.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitea/workflows/tests.yml

@@ -26,13 +26,6 @@ jobs:
           extensions: mbstring, pdo_sqlite, sodium, redis, bcmath, gd, zip
           coverage: none
 
-      - name: Cache Composer packages
-        uses: actions/cache@v4.1.2
-        with:
-          path: ~/.cache/composer
-          key: composer-${{ hashFiles('composer.lock') }}
-          restore-keys: composer-
-
       - name: Install PHP dependencies
         # Dist downloads come from GitHub, which rate-limits anonymous callers —
         # on a shared IP that is a coin flip. Falling back to source clones keeps
@@ -59,13 +52,6 @@ jobs:
         with:
           node-version: '22'
 
-      - name: Cache npm packages
-        uses: actions/cache@v4.1.2
-        with:
-          path: ~/.npm
-          key: npm-${{ hashFiles('package-lock.json') }}
-          restore-keys: npm-
-
       - name: Install JS dependencies
         run: npm ci --no-fund --no-audit